Mars Without the Southern Perennial CO₂ Cover

The Martian South Polar Layered Deposits (SPLD) are composed mostly of ice and dust with a thin perennial CO2 cover and some internal CO2 ice layers. In the North, the seasonal CO2 cap is lost during summer, allowing H2O ice to sublimate into the atmosphere. In the South, the perennial CO2 cover prevents H2O ice sublimation. This work uses the Mars Planetary Climate Model to investigate how the H2O and CO2 cycles are affected if the thin perennial CO2 SPLD cover is lost. We find that during southern summer, the atmospheric water content will more than double in the south polar region. However, on a global scale, the NPLD is still the dominant source of humidity because of its larger surface area. When exposing some of the South Polar Cap buried water ice, the south polar cap becomes the dominant source of atmospheric humidity due to Mars's spin-orbital alignment.